Validation of an Endoscopic Landmark for Injection of Internal Branch of Superior Laryngeal Nerve - Original Report - Open Access

Sep 29, 2026

Objective: Validate a novel transnasal endoscopic method to accurately target the internal branch of the superior laryngeal nerve via the piriform sinus, aiming to improve outcomes for laryngeal sensory dysfunction. Methods: Eight cadaveric larynges were studied using a 3D-printed model; the piriform sinus quadrant was marked endoscopically with toluidine blue, and landmark distances to the iSLN confluence were quantified. Results: Mean ink-to-confluence distance was 5.38 mm with less variability than external landmarks. Conclusion: The transnasal approach is anatomically reliable and may outperform traditional techniques.

LanguageEnglish

CategoryHealthcare

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Pages7

Reading Time18 min

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Abstract

Objective

Methods

Results

Conclusion

Introduction

Clinical problem and existing treatments

Rationale for transnasal endoscopic approach

Materials and Methods

Study design and specimens

3D printing

The Laryngoscope ORIGINAL REPORT OPEN ACCESS Validation of an Endoscopic Landmark for Injection of Internal Branch of Superior Laryngeal Nerve Yuki Tanigami1 | David Hortobagyi2 | Andrew J. Bowen3 | Chelsea Kruse1 | Seth H. Dailey1 1Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA | 2Department of Otorhinolaryngology–Head and Neck Surgery, Medical University of Vienna, Vienna, Austria | 3Metrohealth Medical Center, Cleveland, Ohio, USA Correspondence: Seth H. Dailey ([dailey@surgery.wisc.edu](dailey@surgery.wisc.edu)) Received: 28 April 2025 | Revised: 16 July 2025 | Accepted: 4 August 2025 Funding: The authors received no specific funding for this work. Keywords: 3D-printed model | internal branch of superior laryngeal nerve | laryngeal sensory dysfunction | transnasal injection ABSTRACT Objective: This study aims to validate a novel transnasal endoscopic approach for accurately targeting the internal branch of the superior laryngeal nerve (iSLN) via the piriform sinus, with the goal of improving treatment outcomes for laryngeal sensory dysfunction (LSD) . Methods: Eight cadaveric larynges were examined using a 3D-printed cadaveric laryngeal model. The superolateral quadrant of the piriform sinus was endoscopically marked with toluidine blue ink. The distance between the ink mark and the iSLN confluence point was measured as well as other landmarks. Results: The mean distance from the ink to the iSLN confluence was 5.38 mm, with significantly less variability than traditional external landmarks. Conclusion: The transnasal approach provides a reliable, anatomically precise method for accessing the iSLN, offering potential advantages over traditional external techniques in the management of LSD. 1 | Introduction Unexplained chronic cough is a challenging clinical entity to treat [1]. Options include systemic medications such as amitriptyline, gabapentin, lyrica, and others; many have demonstrated successful suppression of cough, but side effects such as dry mouth, sedation, and dizziness in the setting of ongoing administration can be barriers to ongoing use [2]. Speech therapy has also proven effective but requires numerous patient visits and ongoing compliance to the strategies, making long-term results questionable [1]. In 2018, Simpson et al. introduced the office-based technique of external needle delivery of steroids and lidocaine to the internal branches of the superior laryngeal nerve [3]. This technique uses anatomic landmarks to guide delivery of the medication to the area of the iSLN as it exits the thyrohyoid membrane. Numerous follow-up studies show favorable short-term suppression of cough and other suspected neurosensory laryngeal disorders such as chronic throat clearing, globus pharyngeus, and paradoxical vocal fold motion [4–6]. A follow-up injection study also shows that bilateral simultaneous injection is safe and efficacious [7]. The short-term efficacy of this technique, however, remains a limitation to wide acceptance. One possible reason for limited duration of effect is anatomic inaccuracy of delivery based upon the external approach; anatomic landmarks may be obscured due to prior | Yuki Tanigami and David Hortobagyi contributed equally to this work.
This study was previously presented as a poster at the American Laryngological Association (ALA) meeting during the Combined Otolaryngology Spring Meeting (COSM), held May 14–18, 2025, in New Orleans, LA, USA. | | --- | | This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
© 2025 The Author(s) . The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc. | 312 The Laryngoscope,

FAQs

What is the main objective of the study?

To validate a transnasal endoscopic approach that precisely targets the internal branch of the superior laryngeal nerve through the piriform sinus for improved management of laryngeal sensory dysfunction.

How did the researchers perform the landmarking and measurements?

They examined eight cadaveric larynges using a 3D-printed model, endoscopically marked the superolateral quadrant of the piriform sinus with toluidine blue, and measured the distance from the mark to the iSLN confluence point.

What were the key results and how did they compare with external landmarks?

The mean distance from the ink mark to the iSLN confluence was 5.38 mm, with significantly less variability than traditional external landmarks.

Sep 29, 2026

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